Load-carrying attachment for motor vehicles

ABSTRACT

A load-carrying attachment for a vehicle to unload cargo from or load cargo onto the vehicle. The attachment includes a pair of spaced horizontal support beam assemblies having first and second ends. A cross beam connects the first ends of the beam assemblies to form a fixed frame with the beam assemblies. The cross beam is attachable to the vehicle such that the assembly is movable along the periphery of the vehicle. The attachment includes a pair of leg members, one of the leg members being attached to one of the support beam assemblies. The leg members include hydraulic cylinders for raising and lowering the support beam assemblies and wheel assemblies which can be employed as wheels when moving the attachment or as bases when the attachment is being employed to load or unload cargo. The attachment further includes a mast which is slidably attached to the beam assemblies such that it is movable along the beam assemblies. The mast is positioned between the beam assemblies. A carriage is slidably attached to the mast such that it is movable along an axis parallel to the longitudinal axis of the mast. A load engaging member is attachable to the carriage. When the load engaging member is engaging a load and attached to the carriage, the carriage and mast can be operated to move the load onto or off of the vehicle.

FIELD OF THE INVENTION

This invention relates to devices for loading cargo onto and unloadingcargo off of motor vehicles. More particularly, this invention relatesto such devices which may be attached to motor vehicles and includeelevators for raising and lowering the cargo.

BACKGROUND OF THE INVENTION

The cost of material handling is a significant portion of the cost ofcertain items, such as items of large bulk and/or of relatively heavyweight. Examples of such items are building materials, i.e., lumber,concrete blocks, pipe, shingles, steel beams, etc.

Such material handling includes shipping the items from the manufacturerthrough the distribution channel to the retailer and from the retailerto the job site at which the materials will be employed. The handling ofthe materials from the manufacturer through the distribution channels isusually accomplished efficiently and at minimal cost, due to the largequantities of goods being handled. However, the handling of the materialfrom the retailer to the job site usually is not as efficient and thusgreatly, and unnecessarily, increases the cost of such goods.

That is, once the items have been purchased at a retail outlet, theymust be transported to the job site. Much effort and cost may beexpended in delivering these items to the job site.

For purposes of illustration, the handling and transport of buildingmaterials is addressed below. While the handling of building materialsis specifically addressed, the devices according to this invention canbe employed to handle many other objects. Building materials arediscussed merely as an example of the types of goods which can behandled, and not as a limitation on the scope of the invention.

Building materials are usually delivered from a retail establishment orwarehouse to a job site via a flat bed truck, delivery van or othercargo carrying vehicle. The building materials are usually loaded ontothe cargo vehicle by a forklift at the retail establishment orwarehouse. Commonly, the smaller building materials, such as concreteblocks, are stacked on wood pallets of uniform size. These wood palletsinclude spaced layers of boards. The fork of the forklift is insertedinto the space between the layers and is operated to lift the pallet andload of concrete blocks onto the cargo vehicle. Drums of materials,lumber, pipe, shingles and other heavy materials are usually handled inthe same manner. Since most business establishments that sell suchbuilding materials have a forklift available, the loading of the vehicleis not usually much of a problem or expense.

The difficulties in delivering items such as building materials usuallyarise at the job site to which such materials are being delivered.

If a forklift is available at the job site, then the materials can beunloaded in the same manner that they were loaded. However, frequently,a forklift is not available at the job site since such materials areusually being delivered to a construction site at which construction hasnot yet begun or is just getting underway. Moreover, the job site may bea single new house, a few new houses or an addition to an existinghouse. The small size of these jobs does not merit the expense of havinga forklift on the job site.

While an apparent solution would be to haul a forklift on the vehiclewith the load, this is not a viable solution because the retailestablishment or warehouse does not usually have spare forklifts to sendout with every truck, the retailer does not want to be liable for damageor injuries incurred using their forklift under these circumstances, andthe forklift would take up valuable payload space and weight on thevehicle cargo bed.

Therefore, often a forklift is not available at the job site to unloadbuilding materials from a cargo vehicle. Under these conditions, themost frequently used method of unloading the vehicle s hand labor.However, this is dangerous, costly and time consuming work. It isdangerous in that the building materials include heavy items which maycause injury to the workers if mishandled or if a worker has an accidentwhile handling the items (such as slipping in mud).

Moreover, this work is costly since a great deal of time is involved inremoving heavy and/or bulky items from a motor vehicle by manual labor.This problem is compounded because the vehicles are usually loaded bythe forklift at the retail establishment.

Further the unloading process usually must involve at least two workersdue to the weight and/or bulk of some of the building materials.

This requires that, at the least, the driver have a helper to unload thevehicle. In circumstances when the materials are being delivered to anew job site, a helper may not be readily at hand. This may result infurther delay as a helper is located and arrives at the job site, or toavoid this delay, a helper must travel with the driver.

If the helper travels with the vehicle, this greatly increases the laborcosts for delivering the goods. If the helper is to be supplied at thejob site, this may make the delivery schedule critical to assure thatthe vehicle arrives at the job site when the worker is present andavailable to help unload. Moreover, the use of a worker at theconstruction site slows down the construction work as the worker's timeis spent unloading vehicles and not doing actual construction tasks.

In view of these problems, certain types of mechanisms have beendeveloped to help unload vehicles with heavy or bulky payloads at jobsites.

One type of such devices is the hydraulic lift tailgate which isemployed with a closed van. This is a tailgate which is normallyperpendicular to the cargo bed of the closed van, but which may beoriented parallel to the bed of the closed van for lifting and loweringcargo. The tailgate can be hydraulically raised and lowered with a loadon it to move the load from the level of the cargo bed of the closed vanto the ground and vice versa. However, while this is an advance in theart, hydraulic lift tailgates still have many disadvantages.

First, the load must still be transferred from all locations on thecargo bed of the closed van to the hydraulic lift tailgate during theunloading process. Then once the load has been lowered to the ground,manual labor must again be employed to move the cargo from the tailgateto the ground. Thus, a substantial amount of manual labor is stillinvolved. The only manual task which the hydraulic lift tailgate rendersunnecessary is the lowering of the payload down from the vehicle bed tothe ground, and vice versa.

Another mechanism which has been developed to unload such vehicles arebuilt-in cranes. These cranes are built as part of the truck, eitherbetween the truck cab and truck bed or on the truck bed. These craneshave the disadvantage of being relatively expensive and undependable.Moreover, the cranes take up valuable payload space. That is, onvehicles having these built-in cranes, less space is available to carrythe cargo, which in turn, means less profit per trip. Further, thecranes are heavy. This may permit the truck to carry less cargo weightsince the crane takes up some of its maximum payload capacity.

Therefore, it is clear that neither the hydraulic lift tailgate or theequipping of cargo vehicles with built-in cranes is an adequate oroptimum solution to the problem of unloading heavy and/or bulky cargo ata job site.

In view of this, many specialty devices have been developed which may beattached to cargo carrying vehicles for loading and unloading cargo.Examples of these devices are disclosed in U.S. Pat. No. 2,702,678issued to Flock, Jr. on Feb. 22, 1955; U.S. Pat. No. 2,732,087 issued toPratt on Jan. 24, 1956; U.S. Pat. No. 2,993,607 issued to Tapper on Jul.25, 1961; U.S. Pat. No. 3,504,810 issued to Walda on Apr. 7, 1970; U.S.Pat. No. 3,715,046 issued to Marklund on Feb. 6, 1973; U.S. Pat. No.3,945,516 issued to Peck et al on Mar. 23, 1976; U.S. Pat. No. 4,249,842issued to Johnson on Feb. 10, 1981 and U.S. Pat. No. 4,498,829 issued toSpikes on Feb. 12, 1985.

Moreover, specialty forklift devices have been developed to address thisproblem. Such forklift devices are disclosed in U.S. Pat. No. 2,962,180issued to Vossenberg on Nov. 29, 1960; U.S. Pat. No. 3,563,341 issued toBuitman on Feb. 16, 1971; U.S. Pat. No. 4,365,921 issued to Brouwer etal on Dec. 28, 1982; U.S. Pat. No. 4,415,302 issued to Brouwer et al onNov. 15, 1983 and U.S. Pat. No. 4,498,837 issued to Kooi et al on Feb.12, 1985.

However, all of these devices are limited in their use. The forkliftdevices must still be provided at each and every job site. The deviceswhich are attachable to a vehicle, disclosed in the first listedpatents, all have the limitation that they cannot remove loads of anysize from all locations of the truck bed without manual labor, which isthe same problem with the hydraulic lift tailgate.

Therefore, it is apparent that there still exists a need in the art fora load-carrying attachment for motor vehicles which can remove loads ofall sizes from all locations on the truck bed. This invention addressesthis need in the art, as well as other needs which are apparent to thoseskilled in the art once given this disclosure.

SUMMARY OF THE INVENTION

This invention provides a load-carrying attachment for a cargo carryingvehicle to unload cargo from or load cargo onto the vehicle. Theattachment includes a pair of spaced horizontal support beam assemblieshaving first and second ends. The beam assemblies are connected andtheir first ends are attachable to the vehicle. The attachment comprisesa pair of leg members, one of the leg members being attached to one ofthe support beam assemblies. The attachment also includes a mast whichis slidably attached to the beam assemblies such that the mast ismovable along the beam assemblies. The mast is positioned between thebeams and is rotatably attached to the beams. Further, the attachmentincludes a carriage slidably attached to the mast such that the carriagecan slide parallel to the longitudinal axis of the mast. A member isremovably attachable to the carriage for engaging a load.

Some embodiments of this invention include a member attached to thevehicle for receiving the first ends of the support beam assemblies.This member may extend along the sides and back of the vehicle such thatthe attachment may be moved completely around the sides and back of thevehicle.

In other embodiments of this invention, a cross beam extends between andis attached to the first ends of the support beam assemblies. Rollersmay be attached to the cross beam and engage the receiving member whichis attached to the vehicle. The receiving member may be hollow tubing.The tubing may be attached underneath the bed of the vehicle.

In yet other embodiments of the invention, the leg members are attachedto the second ends of the support beam assemblies and are extendable andretractable to vary the height of these second ends. The leg members mayinclude a hydraulic cylinder having an extendable arm. Wheel members maybe rotatably attached to the extendable arms. Moreover, the wheelmembers may be pivotably attached to the extendable arms such that thewheel members can be oriented in parallel or perpendicular to theextendable arms.

In further embodiments, the mast includes a cross beam and membersattached on the ends of the cross beam that slidably engage the supportbeam assemblies. These members may be slide shoes.

The mast may also include spaced elongated upright members. The carriagemay be slidable along these upright members. Further, the mast mayinclude a hydraulic cylinder which is operable to raise and lower thecarriage.

The carriage may have a front side which faces the first ends of thesupport beam assemblies and a back side which faces away from the firstends. The load engaging member is attachable to the carriage such thatit may extend forward from the front side of the carriage or rearwardfrom the back side of the carriage.

In some embodiments of this invention, the mast and carriage may have aposition in which the mast and carriage do not extend above the top ofthe support beam assemblies.

The devices according to this invention have many advantages over theprior devices for loading cargo onto and unloading cargo off of cargovehicles. Such advantages include the fact that the use of devicesaccording to this invention minimizes the manual labor required toperform these tasks.

The devices according to this invention can be employed to unload a loadfrom any location on the vehicle cargo bed without manual labor. Thus,loads at the front of the vehicle cargo bed can be engaged and removedas easily as loads located at the rear of the vehicles. This could notbe previously done with the unloading devices for closed vans.Furthermore, with respect to the flat bed trucks, the devices aremovable to any position on all sides and the back of the cargo bed of aflat bed truck.

Another advantage of devices according to this invention is that suchdevices can handle and transport items of almost any width and height.Items of excessive height and width can be loaded onto or unloaded froma cargo vehicle with these devices without manual labor.

A further advantage of these devices is that they are attachable tovehicles and may be carried under the bed of the vehicles to and fromjob sites. Thus, the devices may always be available, even at the mostremote job site.

A further advantage is that the devices according to the invention maybe stored under the vehicle cargo bed when not in use. The devices donot take up valuable payload space on the vehicle cargo bed. In thealternative, the devices can be easily removed from the vehicle to beemployed with another vehicle, or for storage.

A further advantage is that the devices according to this invention aresafe. No manual lifting of any items is involved. Moreover, the devicesare very sturdy, stable and balanced when loads are being handled.

Other advantages include the fact that the devices according to thisinvention are easy to use and when properly used, quickly unloadvehicles. This reduces the cost involved in loading and unloading cargovehicles. Also, skilled labor is not necessary to operate the device.

Yet another advantage is that the devices according to this inventioncan be employed in uneven terrain and on sloped surfaces. The legmembers can be individually employed to adjust the height of the supportbeam assemblies relative the ground surface.

A further advantage of these devices is that the devices can be easilyand quickly installed on most existing cargo vehicles. Thus, the devicesdo not have to come as original equipment, but can be installed on motorvehicles already in use.

Certain embodiments of this invention will now be described with respectto the Figures, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of one embodiment of this invention affixed to aflat bed truck.

FIG. 2 is a partial side view of the embodiment of this inventionillustrated in FIG. 1 in engagement with the rear end of a flat bedtruck.

FIG. 3 is a side view, partially cross-sectioned for clarity, of theembodiment of this invention illustrated in FIGS. 1 and 2 in engagementwith the side of a flat bed truck.

FIG. 4 is a top view, partially cross-sectioned for clarity, of theembodiment of this invention illustrated in FIGS. 1-3 in engagement witha flat bed truck.

FIG. 5 is a cross-sectional view taken along reference line 5--5 of FIG.4.

FIG. 6 is a cross-sectional view taken along reference line 6--6 of FIG.7.

FIG. 7 is a partial rear view, partially cross-sectioned for clarity, ofthe mast, horizontal support beam assemblies and leg support assembliesof the embodiment of this invention illustrated in FIGS. 1--6.

FIG. 8 is a rear view, partially cross-sectioned for clarity, of themast (including the elevator), horizontal support beam assemblies andleg support assemblies of the embodiment of this invention illustratedin FIGS. 1-7.

FIG. 9 is a top view of the carriage of the embodiment of this inventionillustrated in FIGS. 1-8.

FIG. 10 is a partial front view of the carriage illustrated in FIG. 9.

FIG. 11 is a top view of the embodiment of this invention illustrated inFIGS. 1-10, illustrating one stop in the unloading of a wide item.

FIGS. 12-15 are side views illustrating, in sequential steps, theprocess of unloading a wide item from a vehicle using the embodiment ofthis invention illustrated in FIGS. 1-11.

FIG. 16 is a partial side view of the left side tube and left turnstileof the embodiment of this invention illustrated in FIGS. 1-15.

FIG. 17 is a top view, partially cut away for clarity, of the embodimentof this invention illustrated in FIGS. 1-16 attached to the side of atruck bed.

FIG. 18 is a partial rear view, partially cross-sectioned for clarity,of the attachment of the mast to one of the horizontal beam assemblies.

FIG. 19 is a schematic drawing illustrating the movement of anattachment according to this invention around a rear corner of a cargovehicle.

FIG. 20 is a rear view illustrating the movement of the embodiment ofthis invention illustrated in FIGS. 1-17 around the periphery of thevehicle.

FIG. 21 is a partial cross-sectional view taken along reference line21--21 of FIG. 8.

FIG. 22 is a partial top view, partially cross-sectioned for clarity, ofthe embodiment of this invention illustrated in FIG. 1-21 attached to atruck bed.

FIG. 23 is a cross-sectional view taken along reference line 23--23 ofFIG. 22.

FIG. 24 is a partial top view of the embodiment of this inventionillustrated in FIGS. 1-23, partially cross-sectioned for clarity,illustrating the turning of the embodiment about the right rear cornerof a truck bed.

FIG. 25 is a partial side view illustrating the tine assembly, mast andone leg support assembly of the embodiment of this invention illustratedin FIGS. 1-24.

FIG. 26 is a rear view of the embodiment of this invention illustratedin FIGS. 1-25, illustrating the embodiment stored under a truck bed.

FIG. 27 is a partial top view of the embodiment of this inventionillustrated in FIGS. 1-26, illustrating the embodiment being placed intoits storage rack under a truck bed.

FIG. 28 is a rear view of the embodiment of this invention illustratedin FIGS. 1-27, illustrating the embodiment being placed into its storagerack under a truck bed.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the Figures, in particular FIG. 1, one embodiment of thisinvention, attachment 30, is illustrated attached to truck 32. Truck 32includes cab 34 and truck bed 36. Truck bed 36 is loaded with items37-46. Items 37-46 can be of any type normally transported by truck. Forpurposes of illustration, the transport and handling of buildingmaterials such as cubes of concrete blocks on wood pallets, bundles oflumber, bundles of piping, stacks of shingles and barrels of asphalt arespecifically addressed herein. However, it is to be understood that thisinvention is not limited to the handling of building materials. Forexample, the load-carrying attachments according to this invention canbe employed to handle agricultural materials, such as fertilizers,herbicides, pesticides, etc.; military goods and items; etc.

Attachment 30 includes horizontal support beam assemblies 48 and 50,front cross beam assembly 52, leg support assemblies 54 and 56 andelevator assembly 58 (see FIGS. 1, 2 and 7).

In addition, in the embodiment of this invention illustrated in theFigures, truck 32 includes tubing 60 and storage rack 62 attached to theunderside of truck bed 36 (see FIGS. 2, 17 and 28).

Tubing 60 is attached to the periphery of the underside of truck bed 36and extends around the sides and back of truck bed 36. Tubing 60includes left tube 64, rear tube 66 and right tube 68. In the embodimentillustrated in the Figures, tubes 64, 66 and 68 are all rectangulartubes of the same size having elongated slits in their outer faces, suchas slit 70 in left tube 64 (see FIG. 2), slit 72 in rear tube 66 (seeFIGS. 20 and 26) and slit 74 in right tube 68 (see FIG. 16). Slits 70,72 and 74 extend the entire lengths of tubes 64, 66 and 68,respectively. The function of slits 70, 72 and 74 will be discussedbelow.

Tube 68 has four doors 61 spaced apart in the bottom thereof. Doors 61are spaced apart a distance equal to the spacing between rollers 120-123(discussed below) and may be rotatably or slidably attached to tube 68.The openings in the bottom of tube 68 resulting from the opening ofdoors 61 are of a size sufficient for rollers 120-123 to pass through.

In addition, tubing 60 includes turnstiles 82 and 84. Turnstiles 82 and84 are identical and can be made of sections of the same tubing as tubes64, 66 and 68. Turnstile 82 is located at the right rear corner of truckbed 36 and turnstile 84 is located at the left rear corner of truck bed36 (see FIG. 17).

Turnstiles 82 and 84 are square (when viewed from the top) and have hole83 in the center of the bottom plate (see FIG. 22). This hole rotatablyengages a bolt or other item such that turnstiles 82 and 84 arepivotable.

Turnstiles 82 and 84 each have open ends 81 and 85 (see FIGS. 16 and 22)and front face 87. Front face 87 has slit 89 (see FIG. 16) therein whichmatches slits 70, 72 and 74. Turnstiles 82 and 84 are spaced from theends of tubes 64, 66 and 68, forming gaps 91, 93, 95 and 97, for thepurposes discussed below.

Tubes 64, 66 and 68 have open slots in their outer faces, such as slot76 in left tube 64 (see FIG. 2), slots 77 and 79 in rear tube 66 (seeFIG. 26) and slot 80 in right tube 68 (see FIG. 18). Slots 76, 77 and 79are spaced equidistance from the center holes 83 in turnstiles 82 and84. The function of all these slots is discussed in detail below.

Horizontal support beam assemblies 48 and 50 are identical and includeI-beams 94 and 96, side plates 98 and 100, back plates 102 and 104, topplates 103 and 105, top guide rods 106 and 108 and bottom guide rods 110and 112, respectively (see FIGS. 7 and 8).

I-beams 94 and 96, side plates 98 and 100, top plates 103 and 105 andguide rods 106, 108, 110 and 112 extend the length of attachment 30.Side plates 98 and 100 are attached to I-beams 94 and 96 by supports(not illustrated) and spaced therefrom (see FIGS. 7 and 8). This enablesthe placement of hydraulic hoses, motors, switches, etc. (not shown) inthe space between I-beams 94 and 96 and side plates 98 and 100. Topplates 103 and 105 are attached to side plates 98 and 100 and spacedabove I-beams 94 and 96, respectively.

End plates 102 and 104 are attached to side plates 98 and 100 and topplates 103 and 105, respectively, to provide a more complete enclosure,thus protecting any hydraulic mechanisms located therein from adverseweather conditions and from other damage. This enclosure also protectspersons working adjacent the device from injury if the hydraulic systemmalfunctions, for example, if one of the hydraulic lines ruptures.

Top guide rods 106 and 108 are attached to the underside of top plates103 and 105, respectively, and extend the entire length of top plates103 and 105. Likewise, bottom guide rods 110 and 112 are affixed to thetop of I-beams 94 and 96, respectively, and extend the entire length ofthe I-beams. In this embodiment, guide rods 106, 108, 110 and 112 have asquare cross section.

Horizontal support beam assemblies 48 and 50 also include rollers 127and 129 which are fixed to the exterior of side plates 98 and 100,respectively, at the front end thereof (see FIGS. 7 and 27). The axes ofrotation of rollers 127 and 129 is perpendicular to the longitudinalaxes of support beam assemblies 48 and 50.

Front cross beam assembly 52 includes outer tube 114, inner tube 116,tees 113, 115, 117 and 118, rollers 120, 121, 122 and 123 and bridge124. Inner tube 116 is located within outer tube 114 (see FIG. 5). Outertube 114 and inner tube 116 extend between, and are connected on theirrespective ends to I-beams 94 and 96, thus forming a fixed frame. In theembodiment illustrated in the Figures, outer tube 114 has a rectangularcross section and inner tube 116 has a circular cross section.

The diameter of the outer surface of inner tube 116 is less than thesmallest width of the inner surface of outer tube 114. For example,inner tube 116 may have a two inch diameter, while outer tube 114 may bethree inches by four inches.

Rollers 120-123 are attached to inner tube 116 by tees 113, 115, 117 and118, respectively. In this embodiment, tees 113, 115, 117 and 118 areequally spaced along inner tube 116. Inner tube 116 is rotatablyreceived within the "tops" of tees 113, 115, 117 and 118. The "stems" oftees 113, 115, 117 and 118 extend through slits 70, 72 or 74 (dependingon the location of attachment 30) in tubes 64, 66 and 68, respectively,and through orifices 126 in outer tube 114 (see FIG. 5). Orifices 126are larger than the diameter of tees 113, 115, 117 and 118 so that tees113, 115, 117 and 118 may rotate around inner tube 116.

The ability of tees 113, 115, 117 and 118 to rotate around inner tube116 renders attachment 30 capable of use on uneven terrain. Rollers120-123 and tees 113, 115, 117 and 118 can rotate around inner tube 116if attachment 30 is placed on terrain of a different height than truckbed 36.

Rollers 120-123 are connected to tees 113, 115, 117 and 118 by shaftssuch as shaft 119 (see FIG. 5). The shafts have one end received withintees 113, 115, 117 and 118, and have rollers 120-123 rotatably attachedto the other end.

Rollers 120-123 are snugly received within tube assembly 60 and thusroll within tubes 64, 66 and 68. Rollers 120-123 roll along theperiphery of truck bed 36 as illustrated by the double-headed arrow inFIG. 4. This permits the entire attachment 30 to be moved around theperiphery of truck bed 36, as desired, and as discussed below.

Bridge 124 is attached on its ends to tees 115 and 117 and is locatedwithin tubing 60 (see FIGS. 4, 22 and 23). Bridge 124 is a flat platewhich has a height greater then the height of slits 70, 72 and 74 sothat bridge 124 does not fit through slots 70, 72 and 74.

Leg support assemblies 54 and 56 are identical and include hollowrectangular tubes 128 and 130, hydraulic cylinders 132 and 134,extendable arms 136 and 138, clevis assemblies 140 and 142 and wheelassemblies 144 and 146, respectively.

Rectangular tubes 128 and 130 are attached to the underside of I-beams94 and 96, respectively, and extend downward therefrom (see FIGS. 3 and7). Rectangular tubes 128 and 130 are hollow tubes which house hydrauliccylinders 132 and 134, respectively. Hydraulic cylinders 132 and 134include extendable arms 136 and 138 which extend downwardly fromhydraulic cylinders 132 and 134 (and thus from tubes 128 and 130).Extendable arms 136 and 138 have clevis assemblies 140 and 142 attachedto their lower ends, respectively. Wheel assemblies 144 and 146 arerotatably attached to clevis assemblies 140 and 142, respectively.

Wheel assemblies 144 and 146 are pivotally attached to extendable arms136 and 138 by clevis assemblies 140 and 142, respectively. Thus, wheelassemblies 144 and 146 can be oriented perpendicularly to extendablearms 136 and 138 or in parallel to extendable arms 136 and 138 (see FIG.8).

Clevis assemblies 140 and 142 are identical and include swivel rodassemblies 137 and 139 which are fixedly attached to the lower ends ofextendable arms 134 and 136, respectively. Swivel rod assemblies 137 and139 are constructed such that the lower ends 141 and 143 are free toswivel relative extendable arms 134 and 136, respectively.

Clevis assemblies 140 and 142 also include clevis 145 and 147 which havethe hubs of wheel assemblies 144 and 146, respectively, rotatablyconnected thereto. Clevis 145 and 147 include left flanges 149 and 151and right flanges 153 and 155, respectively, which project outwardlyfrom the wheels of wheel assemblies 144 and 146, normal to the wheels.Lower ends 141 and 143 are received between left flanges 149 and 151 andright flanges 153 and 155, respectively.

Lower ends 141 and 143 and flanges 149, 151, 153 and 155 have orificestherethrough to receive pins 133 and 135. Pins 133 and 135 pivotallyattach flanges 149, 151, 153 and 155, and thus wheel assemblies 144 and146, to lower ends 141 and 143 of swivel rod assemblies 137 and 139.Therefore, wheel assemblies 144 and 146 may pivot relative extendablearms 136 and 138.

A latch assembly such as latch 157 (see FIG. 8) can be employed toretain a wheel assembly parallel to an extendable arm.

Elevator assembly 58 includes a mast comprised of base plate 148,upright channels 150 and 152, front plates 154 and 156, slide shoes 158and 160 and hydraulic cylinder 162. Elevator assembly 58 also includescarriage 164, which is slidably attached to the mast, as discussedbelow.

Base plate 148 is a rectangular plate of uniform thickness. Uprightchannels 150 and 152 are affixed, on end, to the narrow ends of baseplate 148 and extend upward therefrom. Channels 150 and 152 are orientedsuch that the open end of the channels face each other (see FIG. 4).Front plates 154 and 156 extend across and are attached to the open endsof channels 150 and 152 at the lower portion of channels 150 and 152,respectively (see FIG. 7). Rollers 166 and 167 are attached to frontplates 154 and 156, respectively (see FIG. 6).

Slide shoes 158 and 160 are attached to upright channels 150 and 152 bybracket assemblies 168 and 170, respectively.

Bracket assemblies 168 and 170 are identical and include steelcylindrical brackets 169, support brackets 171 and sleeves 173. In theembodiment illustrated in the Figures, a bracket 169 is attached to theouter face of each of upright channels 150 and 152. Brackets 169 arethreaded in the center to receive sleeves 173. Support brackets 171 arearc-shaped plates attached underneath brackets 169 for reinforcingsupport. Sleeves 173 are elongated, hollow cylinders which threadedlyengage brackets 169. Sleeves 173 extend outward from upright channels150 and 152.

Slide shoes 158 and 160 are received between top plates 103 and 105 andI-beams 94 and 96, respectively. Shoes 158 and 160 have grooves in thetop and the bottom thereof to engage top guide rods 106 and 108 andbottom guide rods 110 and 112, respectively. Thus, slide shoes 158 and160 are designed to slide back and forth along the top of I-beams 94 and96 between I-beams 94 and 96 and top plates 103 and 105.

Rods 175 and 177 are attached to slide shoes 158 and 160, respectively,and extend from slide shoes 158 and 160 inwardly. Rods 175 and 177 arerotatably received in sleeves 173 of bracket assemblies 168 and 170 toaffix slide shoes 158 and 160 to upright channels 150 and 152,respectively.

Pins 179 and 181 are employed to retain elevator assembly 58perpendicular to horizontal support beam assemblies 48 and 50. Pins 179and 181 are received within holes in flanges 169, support brackets 171,sleeves 173 and rods 175 and 177 (see FIGS. 8, 18 and 21). When pins 179and 181 are received by these holes, elevator assembly 58 is retainedperpendicular to support beam assemblies 48 and 50. When pins 179 and181 are removed, elevator assembly 58 may be rotated relative supportbeam assemblies 48 and 50.

Hydraulic cylinder 162 is located in the middle of elevator assembly 58(see FIGS. 7 and 8). The bottom of hydraulic cylinder 162 is attached tothe central portion of base plate 148 and hydraulic cylinder 162 extendsupward therefrom. Hydraulic cylinder 162 includes extendable arm 172which extends upward. Axle 174 is attached to the upper end ofextendable arm 172. Axle 174 has sprockets 176 and 178 affixed on eachend thereof. Chains 180 and 182 interface with sprockets 176 and 178.

Carriage 164 includes upright elongated channels 184 and 186, crossplates 188, sprocket assemblies 190-193, front upper plate 194, frontlower plate 196, back upper plate 198, back lower plate 199 and sideplates 200 and 202 (see FIGS. 9 and 10). The open end of channels 184and 186 are affixed to side plates 200 and 202, respectively. Sideplates 200 and 202 extend between and are connected on their ends tocross plates 188 to form a fixed rectangular frame. Sprocket assemblies190-193 are attached to the interior of cross plates 188. Upper andlower plates 194, 196, 198 and 199 are flat rectangular plates which areattached to the exterior of cross plates 188.

Upper plates 194 and 198 have notches 195 and 197 in the upper back edgethereof, respectively. Notches 195 and 197 extend the length of upperplates 194 and 198. The function of notches 195 and 197 is discussedbelow.

Elevator assembly 58 is assembled such that upright channels 184 and 186are received within upright channels 150 and 152 (see FIGS. 4 and 6).That is, channels 184 and 186 are received between channels 150 and 152and rollers 166 and 167, respectively. Rollers 166 and 167 can be amultiplicity of rollers arranged at any angle with respect to channels150, 152, 184 and 186.

Chains 180 and 182 extend between and interface with sprockets 176, 190and 191 and sprockets 178, 192 and 193, respectively.

Attachment 30 includes a mechanism to slide elevator assembly 58relative to horizontal support beam assemblies 48 and 50. This mechanismincludes hydraulic motor assemblies 204 and 206, front sprockets 208 and210, rear sprockets 212 and 214 and chains 216 and 218 (see FIGS. 2 and4). The hydraulic motor assemblies 204 and 206 are mounted on top ofI-beams 94 and 96 and front cross beam assembly 52. Front sprockets 208and 210 and rear sprockets 212 and 214 are rotatably affixed to I-beams94 and 96, respectively. The output of motor assemblies 204 and 206 isshafts which rotate front sprockets 208 and 210. Hydraulic motorassemblies 204 and 206 have reversible hydraulic motors so that frontsprockets 208 and 210 can be driven in either direction. Rear sprockets212 and 214 are idler sprockets.

One end of chains 216 and 218 is affixed to the front of slide shoes 158and 160, respectively. Chains 216 and 218 are then looped around frontsprockets 208 and 210, rear sprockets 212 and 214, and then reattachedto the back side of slide shoes 158 and 160, respectively.

Attachment 30 also includes forklift tines assembly or fork 230 which isattachable to carriage 164. Fork 230 includes platform tines 232 andupright member 234. Carriage 164 is designed such that fork 230 can beattached to either the front side or back side of carriage 164. This isaccomplished by hook angle 231 which is affixed to the top back edge ofupright member 234. Hook angle 231 is designed to engage notches 195 and197 (see FIG. 25). When hook angle 231 is in engagement with eithernotch 195 or 197, the lower portion of upright member 234 is in abutmentwith one of the lower plates 196 and 199 to retain fork 230.

In the embodiment illustrated in the Figures, storage rack 62 is locatedunderneath truck bed 36, behind the rear wheels of truck 32 and includesslidable drawers 220 and 221, elongated angles 222 and 224, a pluralityof hangers 226, front cross support 260 and back cross support 262 (seeFIGS. 26-28). Hangers 226 are attached to, and extend downward from, thebottom of truck bed 36. Elongated angles 222 and 224 are connected tohangers 226 and extend perpendicular to the longitudinal axis of truckbed 36. Cross supports 260 and 262 are attached to and extend betweenangles 222 and 224 to form the basic frame of storage rack 62.

Angles 222 and 224 have vertical legs 236 and 238 and horizontal legs240 and 242, respectively. Angles 222 and 224 are oriented such thatvertical leg 236 is rearward of horizontal leg 240 and extends upwardtherefrom and vertical leg 238 is forward of horizontal leg 242 andextends upward therefrom. Vertical legs 236 and 238 have identical slits244 therein which extend longitudinally from one end of the legs topoints close to the second end.

Hangers 226 are L-shaped. Angles 222 and 224 are attached to the base ofthe "L" of hangers 226. The top of the upright flange of hangers 226 areattached to the underside of truck bed 36.

Slidable drawers 220 and 221 are also L-shaped and include base legs 246and upright legs 248. Base legs 246 are flat rectangular plates.

Upright legs 248 are comprised of front plates 256 and rear plates 258.Front plates 256 and rear plates 258 are vertical, spaced plates whichreceive rollers 127 and 129 therebetween.

Storage rack assembly 62 also includes front drawer hangers 250 and reardrawer hangers 252. Base legs 246 are slidably received and retained infront hangers 250 and rear hangers 252. Stop bolts 254 which passthrough base legs 246 are provided to prevent base legs 246 fromcompletely passing through rear hangers 252. If stop bolts 254 areremoved, the entire attachment 30 can be removed from truck bed 36.

The embodiment of this invention illustrated in the Figures, attachment30, is utilized as follows. First, tubing 60 is affixed to the undersideof truck bed 36 as discussed above. Also, storage rack 62 is affixedunder the vehicle, either in front of or behind the rear wheels thereof(see FIGS. 2 and 17). Assuming attachment 30 is in storage rack 62 (asshown in FIG. 26) and that it is desired to employ assembly 30 to unloadone or more of items 37-46 from truck bed 36, the following steps aretaken.

When attachment 30 is in storage rack 62, elevator assembly 58 ispositioned parallel to horizontal support beam assemblies 48 and 50.Support beam assemblies 48 and 50 and elevator assembly 58 are restingon elongated angles 222 and 224. Moreover, extendable arms 136 and 138are fully retracted into hydraulic cylinders 132 and 134, respectively,so that wheel assemblies 144 and 146 are at their maximum height fromthe ground.

Thus, to utilize attachment 30, attachment 30 must be removed fromstorage rack 62 by first sliding attachment 30 out of storage rack 62 inthe direction of the arrow in FIG. 17. During this movement, rollers 127and 129 rotatably engage slits 244 in elongated angles 222 and 244.

Attachment 30 is slid out of rack 62 until rollers 127 and 129 exitslits 244 and enter drawers 220 and 221. Drawers 220 and 221 are thenslid outward to the position shown in FIG. 28. During this movement,base legs 246 slide relative front drawer hangers 250 and rear drawerhangers 252. Stop bolts 254 engage rear drawer hangers 252 to preventdrawers 220 and 221 from being pulled out too far.

Doors 61 are opened. Hydraulic cylinders 132 and 134 are operated tolower wheel assemblies 144 and 146 in contact with the ground. Elevatorassembly 58 can be rotated relative to horizontal beam supportassemblies 48 and 50 and latched in place by pins 179 and 181 such thatelevator assembly 58 is approximately perpendicular to the groundsurface.

Next, hydraulic cylinders 132 and 134 can be further operated to liftattachment 30 (specifically, rollers 127 and 129) out of drawers 220 and221, through the openings corresponding to doors 61 and into right tube68. Doors 61 are closed. Drawers 220 and 221 are then pushed back undertruck bed 36. Wheel assemblies 144 and 146 are swivelled about swivelrod assemblies 137 and 139, respectively, so that the wheels areoriented parallel to the side of truck bed 36.

Once these steps have been taken, attachment 30 is ready to be movedaround the periphery of truck bed 36 to its desired position, withrollers 120-123 moving in tubing 60 and the wheels of wheel assemblies144 and 146 in contact with the ground.

If it is desired to remove one of the loads 41-46 (see FIG. 1),attachment 30 is merely rolled along the right edge of the truck bed toa position centered on the desired load. During this movement, rollers121-123 and bridge 124 are in engagement with right tube 68 and tees113, 115, 117 and 118 are slidably received within slit 74.

If the item to be removed from truck bed 36 is located at the rear ofthe truck or on the left side of truck bed 36 (items 37-40), thenattachment 30 must be maneuvered around at least one rear corner oftruck bed 36.

This is accomplished by moving attachment 30 to the rear of truck bed36. Turnstile 82 is aligned with right tube 68. As attachment 30 nearsthe rear of truck bed 36, rollers 120 and 121 exit right tube 68 andpass through turnstile 82. Specifically, rollers 120 and 121 passthrough gap 97 and open ends 81 and 85 of turnstile 82. Tees 113 and 115will pass through slit 89 in front face 87 of turnstile 82. Bridge 124is received within turnstile 82.

Attachment 30 is moved rearward until roller 122 is in gap 97, roller123 is adjacent slot 80 in right tube 68 and bridge 124 is centered inturnstile 82 (see FIG. 24).

Once attachment 30 is in this position, the entire attachment 30 can berotated with turnstile 82 as shown in FIG. 24. As turnstile 82 andattachment 30 are rotated, roller 123 passes through slot 80 out ofright tube 68 and roller 122 exits gap 97.

As the rotation illustrated in FIG. 24 is continued, roller 120 passesthrough slot 79 in rear tube 66 and is received and positioned withinrear tube 66. Roller 121 is received within gap 95 and turnstile 82 isaligned with rear tube 66. The operator can then push attachment 30along the rear end of truck bed 36. As this movement is commenced,roller 121 will enter rear tube 66, and rollers 122 and 123 will passthrough turnstile 82 and gap 95 and enter rear tube 66.

In this manner, attachment 30 can be positioned anywhere along the rearend of truck bed 36 by moving rollers 120-123 and bridge 124 throughrear tube 66 and tees 113, 115, 117 and 118 through slit 72.

If it is desired to position attachment 30 around the left side of truckbed 36 to unload one of items 37-40, attachment 30 is rotated withturnstile 84 in the same manner as it was rotated with turnstile 82.That is, attachment 30 is wheeled along rear tube 66 until rollers 120and 124 pass out the end of rear tube 66, pass through gap 93, and passthrough turnstile 84 which is in alignment with rear tube 66. Thismovement is continued until roller 127 is positioned in gap 93 androller 123 is adjacent slot 77. Turnstile 84 is then rotated until it isaligned with left tube 64, with roller 120 entering left tube 64 throughslot 76 and roller 121 being received in gap 91.

Attachment 30 can then be positioned adjacent any of the items 37-40 asdesired to unload any such items (for example see FIG. 1 whereinattachment 30 is positioned to unload item 40).

Once attachment 30 is positioned adjacent the load or item which it isto be employed to unload, the various elements are further operated asfollows.

First, extendable arms 136 and 138 are retracted to lift wheelassemblies 144 and 146 off the ground sufficiently to enable clevis 145and 147 and wheel assemblies 144 and 146 to be pivoted about pins 133and 135, respectively. Wheel assemblies 144 and 146 are then pivotedsuch that the wheels are perpendicular to the extendable arms 136 and138. Latches 157 can be employed to retain the wheels perpendicular toextendable arms 136 and 138. Hydraulic cylinders 132 and 134 are thenoperated to lower extendable arms 136 and 138 until wheel assemblies 144and 146 rest on the ground, approximately parallel to the ground.

Next, fork 230 is attached to the front side of carriage 164 by engaginghook angle 231 in slot 195 of front upper plate 194. Fork 230 is thenpositioned vertically, by operating hydraulic cylinder 162, to be thesame height as the underside of the item to lifted or as the gap in thewood pallet. The raising and lowering of fork 230 by hydraulic cylinder162 is accomplished as follows.

Hydraulic cylinder 162 functions to raise and lower extendable arm 172.Extendable arm 172 in turn, through axle 174, sprockets 176, 178 and190-193, and chains 180 and 182, raises and lowers carriage 164.Specifically, extendable arm 172 raises axle 174 and sprockets 176 and178. Sprockets 176 and 178 are connected to sprockets 190-193 by chains180 and 182. Thus, sprockets 190 and 193 and carriage 164 are alsoraised. Fork 230 is attached to carriage 164 as discussed. Carriage 164is guided vertically by the interaction of channels 184 and 186 withinchannels 150 and 152, and rollers 166 and 167, respectively.

Once fork 230 is at the desired height, elevator assembly 58 is movedforward so that fork 230 engages the underside of the item or the woodpallet. This movement is accomplished by hydraulic motors 204 and 206which rotate front sprockets 208 and 210, respectively. As discussedabove, chains 216 and 218 are in engagement with front sprockets 208 and210 and rear sprockets 212 and 214, respectively, such that chains 216and 218 are driven in a loop by motors 209 and 206.

The ends of chains 216 and 218 are attached to slide shoes 158 and 160,respectively. Elevator assembly 58 is affixed to slide shoes 158 and 160by rods 175 and 177 and bracket assemblies 168 and 170, respectively.

Thus, rotation of front sprockets 208 and 210 pulls slide shoes 158 and160 in the direction sprockets 208 and 210 are rotating. This slidesslide shoes 158 and 160 along the top of I-beams 94 and 96,respectively, and thus slides elevator assembly 58 relative beam supportassemblies 48 and 50.

This movement is continued until fork 230 engages the underside of theitem or the wood pallet being removed. Once fork 230 is in engagementwith the item or pallet being removed, carriage 164, and thus fork 230,is further raised by hydraulic cylinder 162. This lifts the item orpallet off truck bed 36. The item can then be removed from the truck bedby reversing the previous direction of sprockets 208 and 210 such thatslide shoes 158 and 160, respectively, are moving away from truck bed36. Once the item or pallet being removed has cleared the edge of truckbed 36, it can be lowered to the ground in one of two ways discussedbelow, depending on the width of the load.

If the width of the load is less than the interior width betweenhorizontal side beam assemblies 48 and 50, the item or pallet can besimply unloaded by lowering carriage 164 via hydraulic cylinder 162until the item or pallet rests on the ground (see FIGS. 3 and 4). Thisis achieved by the reverse of the process discussed above. That is,extendable arm 172 is lowered, which lowers axle 174 and sprockets 176and 178, which in turn lowers sprockets 190-193 and carriage 164.

Once the load or item is on the ground, elevator assembly 58 can befurther slid backwards away from the truck bed 36 until fork 230 isclear of the item or withdrawn from the wood pallet being unloaded.Carriage 164 can then be raised and attachment 30 repositioned to moveanother load or attachment 30 can be redirected into storage rack 62.

However, obviously a different approach must be taken to unload the itemif the item or pallet being removed is wider than the space betweenhorizontal support beams assemblies 48 and 50 (for example, load 40).

In this situation, the same initial steps as taken in unloading a narrowload are followed, up to when the wide load (load 40) clears truck bed36. Once load 40 has cleared truck bed 36, the operator continuesbacking load 40 up a distance at least equal to the length of elevatorassembly 58 and fork 230 parallel to the longitudinal axis of horizontalsupport beam assemblies 48 and 50 (see discussion below). Carriage 164is then lowered until load 40 is resting across horizontal support beamassemblies 48 and 50 (see FIGS. 11 and 12).

Elevator assembly 58 is slid further away from truck bed 36 until fork230 clears load 40. Hydraulic cylinder 162 is then operated to lowercarriage 164 to its lowermost position. Fork 230 is removed from thefront side of carriage 164 by removing hook angles 231 from slot 195 andis attached to the back side of carriage 164 by inserting hook angles231 into slot 197 (see FIG. 25). Elevator assembly 58 is slid towardstruck bed 36, as shown in FIG. 13, with elevator assembly 58 fittingbeneath load 40.

Once elevator assembly 58 is positioned between truck bed 36 and load40, carriage 164 can be raised and elevator assembly 58 slid backwarduntil fork 230 is brought into engagement with the opposite side of load40 previously engaged (see FIG. 14). Carriage 164 can then be raised tolift load 40 off of horizontal support beam assemblies 48 and 50.Hydraulic motors 204 and 206 are operated to move slide shoes 158 and160, respectively, and elevator assembly 58 rearward until load 40 isbeyond the back end of attachment 30. Hydraulic cylinder 162 is thenoperated to lower load 40 to the ground as shown in FIG. 15.

Of course, items can be loaded onto truck bed 36 in the same manner,following the reverse steps.

When it is desired to relocate attachment 30 in storage rack 62, thereverse steps from those described above are followed. First, hydrauliccylinders 132 and 134 are operated to lift wheel assemblies 144 and 146off the ground. Wheel assemblies 144 and 146 are then pivoted 90° sothat they are perpendicular to the ground surface and to the horizontalsupport beam assemblies 48 and 50. Hydraulic cylinders 132 and 134 arethen operated to lower wheel assemblies 144 and 146 until the wheels areback in contact with the ground. Attachment 30 can then be pushed backaround the periphery of the truck bed in the same manner as it was movedinto position.

Once attachment 30 is positioned adjacent storage rack 62 with rollers120-123 positioned above doors 61, drawers 220 and 221 are slid out tothe position illustrated in FIG. 28. Rollers 127 and 129 are positionedabove the slots formed by front plates 256 and rear plates 258 ofdrawers 220 and 221, respectively. Pins 179 and 181 are withdrawn andelevator assembly 58 rotated to be approximately parallel horizontalsupport beam assemblies 48 and 50. Rod 264 can be placed across supportbeam assemblies 48 and 50 to support elevator assembly 58 in thisposition (see FIG. 27). Doors 61 are opened.

Hydraulic cylinders 132 and 134 are operated to lower attachment 30until rollers 127 and 129 pass between front plates 256 and rear plates258 and are in alignment with slits 244 in elongated angles 222 and 224,respectively. Wheel assemblies 144 and 146 are swivelled, via swivel rodassemblies 134 and 139, about extendable arms 136 and 138, respectively,such that the wheels are parallel to horizontal support beam assemblies48 and 50.

Attachment 30 can then be pushed inward until rollers 127 and 129 reachthe ends of the slits 244 in elongated angles 22 and 224, respectively.Drawers 220 and 221 are pushed to the inner position.

When attachment 30 is properly placed with storeage rack 62, no partthereof extends beyond the side of truck bed 36.

Once given the above disclosure, many other modifications, improvementsand embodiments will become obvious to those skilled in the art. Allsuch other modifications, improvements and embodiments are considered tobe within the scope of this invention as defined by the followingclaims:

I claim:
 1. A load-carrying attachment for a cargo carrying vehicle tounload cargo from or load cargo onto said vehicle when said attachmentis attached to said vehicle, said attachment comprising:a pair of spacedhorizontal support beam assemblies having first and second ends, saidbeam assemblies being connected, said first ends of said support beamassemblies being attachable to said vehicle; first and second legmembers, said first leg member being attached to one of said supportbeam assemblies, said second leg member being attached to the other ofsaid support beam assemblies; a mast slidably attached to said beamassemblies such that said mast is movable along said beam assemblies,said mast being positioned between said beam assemblies, said mast alsobeing rotatably attached to said beam assemblies; a carriage slidablyattached to said mast such that said carriage can slide parallel to thelongitudinal axis of said mast; first means removably attachable to saidcarriage for engaging a load; and receiving means attached to saidvehicle for receiving said first ends of said support beam assemblies,said receiving means extending along the sides and back of said vehiclesuch that said attachment may be moved around the sides and back of saidvehicle; wherein said attachment is capable of unloading cargo from orloading cargo onto said vehicle when said horizontal support beamassemblies are attached to said vehicle.
 2. A load-carrying attachmentaccording to claim 1 further comprisinga cross beam attached to thefirst ends of said support beam assemblies; and rollers attached to saidcross beam which engage said receiving means.
 3. A load-carryingattachment according to claim 2 whereinsaid receiving means is hollowtubing which receives said rollers therein.
 4. A load-carryingattachment according to claim 3 whereinsaid tubing is attachedunderneath the bed of said vehicle.
 5. A load-carrying attachmentaccording to claim 1 whereinsaid leg members are attached to said secondends of said support beam assemblies; said leg members are extendableand retractable to vary the height of said second ends of said supportbeam assemblies.
 6. A load-carrying attachment according to claim 5whereinsaid leg members have top and bottom ends; said top ends beingattached to said support beam assemblies; said bottom ends including awheel member.
 7. A load-carrying attachment according to claim 6whereinsaid leg members include a hydraulic cylinder having anextendable arm; said wheel members being rotatably attached to saidextendable arms; said wheel members being pivotally attached to saidextendable arms such that said wheel members can be oriented in parallelor perpendicular to said extendable arms.
 8. A load-carrying attachmentaccording to claim 1 whereinsaid mast includes a cross beam and meansfor engaging said support beam assemblies such that said cross beam ismovable along said support beam assemblies; said means being located onthe ends of said cross beam.
 9. A load-carrying attachment according toclaim 8 whereinsaid support beam assemblies include an elongated beam;said means for engaging said support beam assemblies are slide shoeswhich are slidable along the top of said elongated beams.
 10. Aload-carrying attachment according to claim 9 whereinsaid mast includesspaced elongated upright members; said carriage being slidable alongsaid upright members.
 11. A load-carrying attachment according to claim10 whereinsaid mast includes a hydraulic cylinder operable to raise andlower said carriage.
 12. A load-carrying attachment according to claim11 whereinsaid carriage has a front side facing said first ends of saidsupport beam assemblies and a back side facing away from said first endsof said support beam assemblies; said first means being selectivelyattachable to said carriage such that said first means extends forwardfrom said front side of said carriage or rearward from said back side ofsaid carriage.
 13. A load-carrying attachment according to claim 12whereinsaid first means is a fork.
 14. A load-carrying attachmentaccording to claim 1 further comprisinga storage rack located underneaththe bed of said vehicle, said storage rack receiving said support beamassemblies, said mast and said carriage therein when said attachment isnot in use.
 15. A load-carrying attachment according to claim 14whereinsaid storage rack is located behind the rear wheels of saidvehicle.
 16. A load-carrying attachment according to claim 1 furthercomprisingsaid receiving means including hollow tubing connected to thesides and back of said vehicle, said tubing having an outer face; across beam attached to said support beams; spaced rollers attached tosaid cross beam, said rollers being received within said hollow tubing;and a cornering mechanism comprising rotatable turnstiles located on thecorners of said hollow tubing, said turnstiles capable of receiving saidrollers therethrough.
 17. A load-carrying attachment for a cargocarrying vehicle to unload or load said vehicle when said attachment isattached to said vehicle, said attachment comprising:a pair of spacedhorizontal support beams having first and second ends; a cross beamextending between and connecting said support beams, said support beamsand said cross beam forming a fixed frame; spaced rollers attached tosaid cross beam; first and second leg members, said first leg memberbeing attached to one of said support beams, said second leg memberbeing attached to the other of said support beams, said leg members eachincluding a hydraulic cylinder assembly to adjust the height of saidsupport beams; a mast slidably attached to said support beams such thatsaid mast is movable parallel to the longitudinal axis of said supportbeams, said mast being positioned between said support beams; a carriageslidably attached to said mast such that said carriage can slideparallel to the longitudinal axis of said mast, said carriage having afront and a back side, said front side facing said cross beam and saidback side facing in the opposite direction; and means attachable to saidcarriage for engaging a load, said means being attached to the front orback side of said carriage; wherein said attachment is capable ofunloading cargo from or loading cargo onto said vehicle when said spacedrollers are in engagement with said vehicle.
 18. A load-carryingattachment for a cargo carrying vehicle to unload cargo from or loadcargo onto said vehicle when said attachment is attached to saidvehicle, said attachment comprising:a pair of spaced horizontal supportbeam assemblies having first and second ends, said beam assemblies beingconnected, said first ends of said support beam assemblies beingattachable to said vehicle, said horizontal support beam assembliesincluding an elongated support beam having a top surface; first andsecond leg members, said first leg member being attached to one of saidsupport beam assemblies, said second leg member being attached to theother of said support beam assemblies; a mast slidably attached to saidbeam assemblies such that said mast is movable along said beamassemblies, said mast being positioned between said beam assemblies,said mast also being rotatably attached to said beam assemblies; acarriage slidably attached to said mast such that said carriage canslide parallel to the longitudinal axis of said mast; and first meansfor engaging a load, said first means being alternatively attachable tosaid carriage such that said means extends forward of said carriage orrearward of said carriage; said mast and carriage having a firstposition wherein said mast and carriage do not extend above said topsurfaces; wherein said attachment is capable of unloading cargo from orloading cargo onto said vehicle when said horizontal support beamassemblies are attached to said vehicle.